Thin luminaires are known in the art. WO2014/164792, for instance, describes a luminaire which includes a mixing chamber having an array of apertures in one wall, a light source to supply light into the mixing chamber, and an array of optics outside the mixing chamber, each positioned to cooperate with a respective one of the apertures to emit light from the mixing chamber as a beam. The shape, size, and/or direction of the output light beam are controllably varied by controlling the shape, size, and/or position of each aperture relative to its associated optic.